Team aims to score cosmic goal

Professional and amateur astronomers are teaming up to study a cosmic "soccer ball" with a tricky goal in mind: understanding how the death throes of a star are affected by the company it keeps.

The focus of this game is Kronberger 61, a planetary nebula discovered several months ago by Austrian amateur astronomer (and professional physicist) Matthias Kronberger. He belongs to a group called the "Deep Sky Hunters," which combs through imagery from the Digital Sky Survey and other sources looking for celestial objects worthy of further study. The hunters have found about 100 faint planetary nebulae, shells of glowing ionized gas that are thrown off by sunlike stars in the waning years of their lives.

Kronberger 61 is worth noting for aesthetic reasons alone: The image above, captured by the Gemini North telescope in Hawaii, highlights the nebula's emissions from twice-ionized oxygen. The dying star can be seen as a point of bluish light close to the center of the ball-shaped nebula.

But this soccer ball, also known as Kn 61, is also notable because of its location. It happens to be within the Kepler planet-hunting probe's field of view, an 105-square-degree area that takes up about as much of the sky as your hand held at arm's length. There's a chance that Kepler could determine whether there are planets or faint companion stars circling Kn 61's main star.

"Kn 61 is among a rather small collection of planetary nebulae that are strategically placed within Kepler's gaze," Orsola De Marco of Australia's Macquarie University said in the Gemini Observatory's news release about the find. "Explaining the puffs left behind when medium-sized stars like our sun expel their last breaths is a source of heated debate among astronomers, especially the part that companions might play. It literally keeps us up at night!"

The Kepler science team has now added Kn 61 to its target list of more than 150,000 stars, and within months, astronomers might be able to determine whether the star has companions, said George Jacoby of the Giant Magellan Telescope Organization and the Carnegie Observatories (Pasadena). "This was not an object that was known by Kepler to be valuable early on," Jacoby told me.

Jacoby serves as principal investigator for the program to get follow-up observations of Kn 61 with Kepler, and also acts as the liaison with the Deep Sky Hunters.

"Without this close collaboration with amateurs, this discovery would probably not have been made before the end of the Kepler mission," Jacoby said in today's news release. "Professionals, using precious telescope time, aren't as flexible as amateurs who did this using existing data and in their spare time. This was a fantastic pro-am collaboration of discovery."

The Deep Sky Hunters have identified yet another planetary nebula in the Kepler field, and possibly a third prospect. Jacoby said astronomers would be playing an "odds game," hoping that one of the nebulae will reveal something interesting about the effects of companion objects on a dying star's gaseous shell. If the gamble pays off, the scientific payoff could be significant.

De Marco said that planetary nebula present a "profound mystery."

"Some recent theories suggest that planetary nebulae form only in close binary or even planetary systems — on the other hand, the conventional textbook explanation is that most stars, even solo stars like our sun, will meet this fate," she said. "That might just be too simple."

Will this pro-am team hit the goal, or will luck be against them? The project has already produced a beautiful image of a ghostly planetary nebula, and it's sparked some intriguing scientific questions. So the way I see it, they've already scored.

Update for 3 p.m. ET: Jacoby sent along further information about Kronberger 61: The star is located in the constellation Lyra, very close to the western edge of Cygnus. Determining its distance "is a very difficult question, because these kinds of objects (planetary nebulae) have been very resistant to having their distances measured accurately." Jacoby's rough estimate is 13,000 light-years, "but it could be half that or twice that." He says Kronberger discovered the nebula in January, using data from the Digital Sky Survey.

"The star is very likely to have a mass about 60 percent that of the sun," Jacoby wrote in his email. "The age of the star is much harder to estimate, but it is likely between 2 billion and 8 billion years old. The nebula around the star was probably blown off about 15,000 to 30,000 years ago (after accounting for the time delay due to the distance of 13,000 light years, or 28,000 to 43,000 years ago if you include that light travel time)."